<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title>图片滑动验证</title>
	</head>
	<style>
		.block {
		  position: absolute;
		  left: 0;
		  top: 0;
		}
		 
		.sliderContainer {
		  position: relative;
		  text-align: center;
		  width: 310px;
		  height: 40px;
		  line-height: 40px;
		  margin-top: 15px;
		  background: #f7f9fa;
		  color: #45494c;
		  border: 1px solid #e4e7eb;
		}
		 
		.sliderContainer_active .slider {
		  height: 38px;
		  top: -1px;
		  border: 1px solid #1991FA;
		}
		 
		.sliderContainer_active .sliderMask {
		  height: 38px;
		  border-width: 1px;
		}
		 
		.sliderContainer_success .slider {
		  height: 38px;
		  top: -1px;
		  border: 1px solid #52CCBA;
		  background-color: #52CCBA !important;
		}
		 
		.sliderContainer_success .sliderMask {
		  height: 38px;
		  border: 1px solid #52CCBA;
		  background-color: #D2F4EF;
		}
		 
		.sliderContainer_success .sliderIcon {
		  background-position: 0 0 !important;
		}
		 
		.sliderContainer_fail .slider {
		  height: 38px;
		  top: -1px;
		  border: 1px solid #f57a7a;
		  background-color: #f57a7a !important;
		}
		 
		.sliderContainer_fail .sliderMask {
		  height: 38px;
		  border: 1px solid #f57a7a;
		  background-color: #fce1e1;
		}
		 
		.sliderContainer_fail .sliderIcon {
		  top: 14px;
		  background-position: 0 -82px !important;
		}
		.sliderContainer_active .sliderText, .sliderContainer_success .sliderText, .sliderContainer_fail .sliderText {
		  display: none;
		}
		 
		.sliderMask {
		  position: absolute;
		  left: 0;
		  top: 0;
		  height: 40px;
		  border: 0 solid #1991FA;
		  background: #D1E9FE;
		}
		 
		.slider {
		  position: absolute;
		  top: 0;
		  left: 0;
		  width: 40px;
		  height: 40px;
		  background: #fff;
		  box-shadow: 0 0 3px rgba(0, 0, 0, 0.3);
		  cursor: pointer;
		  transition: background .2s linear;
		}
		 
		.slider:hover {
		  background: #1991FA;
		}
		 
		.slider:hover .sliderIcon {
		  background-position: 0 -13px;
		}
		 
		.sliderIcon {
		  position: absolute;
		  top: 15px;
		  left: 13px;
		  width: 14px;
		  height: 12px;
		  background: url(../img/icon_light.f13cff3.png) 0 -26px;
		  background-size: 34px 471px;
		}
		 
		.refreshIcon {
		  position: absolute;
		  right: 0;
		  top: 0;
		  width: 34px;
		  height: 34px;
		  cursor: pointer;
		  background: url(../img/icon_light.f13cff3.png) 0 -437px;
		  background-size: 34px 471px;
		}
	</style>
	<body>
	<div id="captcha"></div>

	</body>
	<script>
		(function (window) {
		  const l = 42, // 滑块边长
		    r = 9, // 滑块半径
		    w = 310, // canvas宽度
		    h = 155, // canvas高度
		    PI = Math.PI
		  const L = l + r * 2 + 3 // 滑块实际边长
		 
		  function getRandomNumberByRange (start, end) {
		    return Math.round(Math.random() * (end - start) + start)
		  }
		 
		  function createCanvas (width, height) {
		    const canvas = createElement('canvas')
		    canvas.width = width
		    canvas.height = height
		    return canvas
		  }
		 
		  function createImg (onload) {
		    const img = createElement('img')
		    img.crossOrigin = "Anonymous"
		    img.onload = onload
		    img.onerror = () => {
		      img.src = getRandomImg()
		    }
		    img.src = getRandomImg()
		    return img
		  }
		 
		  function createElement (tagName, className) {
		    const elment = document.createElement(tagName)
		    elment.className = className
		    return elment
		  }
		 
		  function addClass (tag, className) {
		    tag.classList.add(className)
		  }
		 
		  function removeClass (tag, className) {
		    tag.classList.remove(className)
		  }
		 
		  function getRandomImg () {
			getRandomNumberByRange(0, 1084);
		    return '../img/background-2.jpg';
		  }
		 
		  function draw (ctx, x, y, operation) {
		    ctx.beginPath()
		    ctx.moveTo(x, y)
		    ctx.arc(x + l / 2, y - r + 2, r, 0.72 * PI, 2.26 * PI)
		    ctx.lineTo(x + l, y)
		    ctx.arc(x + l + r - 2, y + l / 2, r, 1.21 * PI, 2.78 * PI)
		    ctx.lineTo(x + l, y + l)
		    ctx.lineTo(x, y + l)
		    ctx.arc(x + r - 2, y + l / 2, r + 0.4, 2.76 * PI, 1.24 * PI, true)
		    ctx.lineTo(x, y)
		    ctx.lineWidth = 2
		    ctx.fillStyle = 'rgba(255, 255, 255, 0.7)'
		    ctx.strokeStyle = 'rgba(255, 255, 255, 0.7)'
		    ctx.stroke()
		    ctx[operation]()
		    ctx.globalCompositeOperation = 'overlay'
		  }
		 
		  function sum (x, y) {
		    return x + y
		  }
		 
		  function square (x) {
		    return x * x
		  }
		 
		  class jigsaw {
		    constructor ({ el, onSuccess, onFail, onRefresh }) {
		      el.style.position = el.style.position || 'relative'
		      this.el = el
		      this.onSuccess = onSuccess
		      this.onFail = onFail
		      this.onRefresh = onRefresh
		    }
		 
		    init () {
		      this.initDOM()
		      this.initImg()
		      this.bindEvents()
		    }
		 
		    initDOM () {
		      const canvas = createCanvas(w, h) // 画布
		      const block = canvas.cloneNode(true) // 滑块
		      const sliderContainer = createElement('div', 'sliderContainer')
		      const refreshIcon = createElement('div', 'refreshIcon')
		      const sliderMask = createElement('div', 'sliderMask')
		      const slider = createElement('div', 'slider')
		      const sliderIcon = createElement('span', 'sliderIcon')
		      const text = createElement('span', 'sliderText')
		 
		      block.className = 'block'
		      text.innerHTML = '向右滑动填充拼图'
		 
		      const el = this.el
		      el.appendChild(canvas)
		      el.appendChild(refreshIcon)
		      el.appendChild(block)
		      slider.appendChild(sliderIcon)
		      sliderMask.appendChild(slider)
		      sliderContainer.appendChild(sliderMask)
		      sliderContainer.appendChild(text)
		      el.appendChild(sliderContainer)
		 
		      Object.assign(this, {
		        canvas,
		        block,
		        sliderContainer,
		        refreshIcon,
		        slider,
		        sliderMask,
		        sliderIcon,
		        text,
		        canvasCtx: canvas.getContext('2d'),
		        blockCtx: block.getContext('2d')
		      })
		    }
		 
		    initImg () {
		      const img = createImg(() => {
		        this.draw()
		        this.canvasCtx.drawImage(img, 0, 0, w, h)
		        this.blockCtx.drawImage(img, 0, 0, w, h)
		        const y = this.y - r * 2 - 1
		        const ImageData = this.blockCtx.getImageData(this.x - 3, y, L, L)
		        this.block.width = L
		        this.blockCtx.putImageData(ImageData, 0, y)
		      })
		      this.img = img
		    }
		 
		    draw () {
		      // 随机创建滑块的位置
		      this.x = getRandomNumberByRange(L + 10, w - (L + 10))
		      this.y = getRandomNumberByRange(10 + r * 2, h - (L + 10))
		      draw(this.canvasCtx, this.x, this.y, 'fill')
		      draw(this.blockCtx, this.x, this.y, 'clip')
		    }
		 
		    clean () {
		      this.canvasCtx.clearRect(0, 0, w, h)
		      this.blockCtx.clearRect(0, 0, w, h)
		      this.block.width = w
		    }
		 
		    bindEvents () {
		      this.el.onselectstart = () => false
		      this.refreshIcon.onclick = () => {
		        this.reset()
		        typeof this.onRefresh === 'function' && this.onRefresh()
		      }
		 
		      let originX, originY, trail = [], isMouseDown = false
		 
		      const handleDragStart = function (e) {
		        originX = e.clientX || e.touches[0].clientX
		        originY = e.clientY || e.touches[0].clientY
		        isMouseDown = true
		      }
		 
		      const handleDragMove = (e) => {
		        if (!isMouseDown) return false
		        const eventX = e.clientX || e.touches[0].clientX
		        const eventY = e.clientY || e.touches[0].clientY
		        const moveX = eventX - originX
		        const moveY = eventY - originY
		        if (moveX < 0 || moveX + 38 >= w) return false
		        this.slider.style.left = moveX + 'px'
		        const blockLeft = (w - 40 - 20) / (w - 40) * moveX
		        this.block.style.left = blockLeft + 'px'
		 
		        addClass(this.sliderContainer, 'sliderContainer_active')
		        this.sliderMask.style.width = moveX + 'px'
		        trail.push(moveY)
		      }
		 
		      const handleDragEnd = (e) => {
		        if (!isMouseDown) return false
		        isMouseDown = false
		        const eventX = e.clientX || e.changedTouches[0].clientX
		        if (eventX == originX) return false
		        removeClass(this.sliderContainer, 'sliderContainer_active')
		        this.trail = trail
		        const { spliced, verified } = this.verify()
		        if (spliced) {
		          if (verified) {
		            addClass(this.sliderContainer, 'sliderContainer_success')
		            typeof this.onSuccess === 'function' && this.onSuccess()
		          } else {
		            addClass(this.sliderContainer, 'sliderContainer_fail')
		            this.text.innerHTML = '再试一次'
		            this.reset()
		          }
		        } else {
		          addClass(this.sliderContainer, 'sliderContainer_fail')
		          typeof this.onFail === 'function' && this.onFail()
		          setTimeout(() => {
		            this.reset()
		          }, 1000)
		        }
		      }
		      this.slider.addEventListener('mousedown', handleDragStart)
		      this.slider.addEventListener('touchstart', handleDragStart)
		      document.addEventListener('mousemove', handleDragMove)
		      document.addEventListener('touchmove', handleDragMove)
		      document.addEventListener('mouseup', handleDragEnd)
		      document.addEventListener('touchend', handleDragEnd)
		    }
		 
		    verify () {
		      const arr = this.trail // 拖动时y轴的移动距离
		      const average = arr.reduce(sum) / arr.length
		      const deviations = arr.map(x => x - average)
		      const stddev = Math.sqrt(deviations.map(square).reduce(sum) / arr.length)
		      const left = parseInt(this.block.style.left)
		      return {
		        spliced: Math.abs(left - this.x) < 10,
		        verified: stddev !== 0, // 简单验证下拖动轨迹，为零时表示Y轴上下没有波动，可能非人为操作
		      }
		    }
		 
		    reset () {
		      this.sliderContainer.className = 'sliderContainer'
		      this.slider.style.left = 0
		      this.block.style.left = 0
		      this.sliderMask.style.width = 0
		      this.clean()
		      this.img.src = getRandomImg()
		    }
		 
		  }
		 
		  window.jigsaw = {
		    init: function (opts) {
		      return new jigsaw(opts).init()
		    }
		  }
		}(window))
	</script>
	<script type="text/javascript">
	  jigsaw.init({
	    el: document.getElementById('captcha'),
	  })
	</script>
</html>